Organization and Summary of Significant Accounting Policies - Revenue Initial Application Period Cumulative Effect Transition (Details) - USD ($) $ in Millions |
Mar. 31, 2018 |
Jan. 01, 2018 |
Dec. 31, 2017 |
|---|---|---|---|
| Revenue, Initial Application Period Cumulative Effect Transition [Line Items] | |||
| Accounts receivable - Trade | $ 1,266 | $ 1,009 | $ 994 |
| Other current assets | 102 | 98 | 97 |
| Other accrued liabilities | 278 | 236 | $ 220 |
| Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member] | |||
| Revenue, Initial Application Period Cumulative Effect Transition [Line Items] | |||
| Accounts receivable - Trade | 10 | 15 | |
| Other current assets | 1 | 1 | |
| Other accrued liabilities | 11 | $ 16 | |
| Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Accounting Standards Update 2014-09 [Member] | |||
| Revenue, Initial Application Period Cumulative Effect Transition [Line Items] | |||
| Accounts receivable - Trade | 1,256 | ||
| Other current assets | 101 | ||
| Other accrued liabilities | $ 267 |